Approach to Vomiting

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Vomiting is an organized, autonomic response that ultimately results in the forceful expulsion of gastric contents through the mouth.

Vomiting in children is most commonly acute infectious gastroenteritis; however, vomiting is a nonspecific symptom and may be initial presentation of serious medical conditions including infections (meningitis, septicemia, urinary tract infection); anatomical abnormalities (malrotation, obstruction, volvulus) and metabolic disease.  Persistent and severe vomiting, if untreated, may result in clinically significant volume depletion and electrolyte disturbances.

Basic anatomy / physiology

Why / How does this occur in children?

Vomiting is a coordinated autonomic response involving neural, hormonal, and muscular responses generated by the reticular formation of the medulla that consists of several scattered groups of neurons.  The vomiting response may be triggered by peripheral and central stimuli (see figure 1).  In particular, the area postrema in the medulla (unprotected by the blood brain barrier) samples peripheral blood and cerebrospinal fluid and likely causes vomiting associated with metabolic disorders and hormones.

Once the vomiting response is triggered, a pattern of somatic muscle action occurs with abdominal, thoracic, and diaphragm muscles contracting against a closed glottis.  The resulting increased intra-abdominal pressure reverses the negative pressure of the esophagus and forces gastric contents upwards. The vomiting response also alters intestinal motility by generating a retroperistaltic contractile complex that moves intestinal contents towards the esophagus.


  • Spitting up: small volumes (usually < 5-10 mL) of vomit during or shortly after feeding, often when being burped; typically caused by rapid/overfeeding and air swallowing
  • Infant regurgitation: vomiting occurring ≥ 2 times per day for at least 3 weeks in the first 1-12 months of life in an otherwise healthy infant; often transient in nature and due to immature gastrointestinal tract


  • Vestibular – motion-sickness and vertigo
  • Infectious – gastroenteritis, septicemia, non-GI infections
  • Cortical – pain, strong emotions, smell, taste
  • Drugs – chemotherapy, opiates
  • Hormonal – pregnancy
  • Metabolic – acidosis, uremia, hyperthyroidism, hypercalcemia, adrenal disorders


  • Pharyngeal stimulation
  • Gastric mucosal irritation
  • Gastric and intestinal distension


History of Presenting Illness

  • Characteristics of vomitus
    • Smell
    • Quantity
    • Colour
    • Blood – bright red/dark red/coffee-ground
    • Bilious
  • Timing
    • Onset
    • Duration
    • Frequency
    • Time of day
    • Triggers
  • Associated Symptoms
    • Diarrhea
    • Fever
    • Abdominal pain/distension
    • Anorexia
    • Stool frequency
    • Urinary Output
    • Headache
    • Vertigo
    • Lethargy
    • Stiff neck
    • Cough
    • Sore throat

Past medical history

  • Chronic illnesses (diabetes)
  • Travel history (infectious gastroenteritis)
  • Sexual history (pregnancy)
    • Ineffective use of birth control
    • Last menstrual period
  • Recent head trauma
  • Toxin exposure



Differential Diagnosis: Common causes of vomiting by age group

Age Acute Chronic

1 month to 1 year


Pyloric stenosis

Hirschsprung’s disease

Acutely evolving surgical abdomen

  • Congenital atresias and stenosis
  • Malrotation
  • Intussusception

Sepsis and non-GI infection

Metabolic disorders

Gastroesophageal reflux disease 

Food intolerance

Congenital atresias and stenosis



Children and adolescents Gastroenteritis 


Sepsis and non-GI infection

Metabolic disorders


Toxic ingestion

Gastroesophageal reflux disease 


Food intolerance

Cyclic vomiting

Intracranial hypertension

Inborn errors of metabolism

Eating disorders

Physical Exam Findings


  • Fever – sign of infection
  • Hypotension, tachycardia – volume loss


  • Consciousness – intracranial hypertension, meningitis, metabolic disorders, toxic ingestion
  • Weight loss – eating disorders, obstruction

Head and Neck

  • Red, bulging tympanic membrane – ear infection
  • Bulging anterior fontanelle  and nuchal rigidity – meningitis
  • Erythematous tonsils – upper respiratory tract infection

Cardiovascular system

  • Tachycardia – infection, dehydration

Abdominal exam

  • Abdominal distention – obstruction, mass, congenital abnormality, organomegaly
  • Bowel sounds – high pitched tinkle (obstruction), absent (ileus)
  • Guarding, rigidity, rebound tenderness – appendicitis, peritoneal inflammation

Skin and extremities

  • Petechiae or purpura – serious infection
  • Skin turgor, capillary refill – dehydration
  • Jaundice – metabolic disorder
  • Rashes – food intolerance, viral infection

Red flags: The following findings are of particular concern:

  • Lethargy and listlessness
  • Inconsolability and bulging fontanelle in an infant
  • Nuchal rigidity, photophobia, and fever in an older child
  • Peritoneal signs or abdominal distention (“surgical” abdomen)
  • Persistent vomiting with poor growth or development

Procedure for Investigation (this will be based on the differential diagnosis)

Condition History and Physical Diagnostic approach
Gastroenteritis Diarrhea (usually), history of infectious contact, fever (sometimes) Clinical evaluation
GERD Fussiness after feeding, poor weight gain Empiric trial of acid suppression
Pyloric stenosis Recurrent projectile vomiting in neonates aged 3-6 weeks, emaciated and dehydrated Ultrasound
Congenital atresia or stenosis Abdominal distension, bilious emesis in first 24-48 hours of life Abdominal X ray 

Contrast enema

Malrotation Bilious emesis, abdominal distention, abdominal pain, bloody stool Abdominal X ray 

Upper GI series with contrast under fluoroscopy

Sepsis Fever, lethargy, tachycardia, tachypnea, widening pulse pressure, hypotension CBC, 

Cultures (blood, urine, CSF)

Food intolerance Abdominal pain, urticarial, eczematous rash Elimination diet
Metabolic disorders Poor feeding, failure to thrive, hepatosplenomegaly, jaundice, dysmorphic features, developmental delays, unusual odors Electrolytes, ammonia, liver function tests, BUN, creatinine, serum glucose, total and direct bilirubin, CBC, PT/PTT 

Further specific tests based on findings

Non-GI infection Fever, localized findings (sore throat, dysuria, flank pain) depending on source Clinical evaluation 

Further tests if needed

Serious infection Meningitis 

  • photophobia, nuchal rigidity, headaches


  • fever, back pain, dysuria
CBC, Cultures (CSF, blood, urine) gram stains 

CBC, Cultures (urine, blood)

Cyclic vomiting At least 3 self-limited episodes of vomiting lasting 12 h,           7 days between episodes,        no organic cause of vomiting Diagnosis of exclusion
Intracranial hypertension Nocturnal wakening, progressive recurrent headache made worse by coughing or Valsalva maneuver, nuchal rigidity, visual changes, weight loss, photophobia Brain CT (without contrast)
Eating disorders Body dysmorphism, teeth erosions, skin lesions on hand (Russell’s sign), binge eating behavior Clinical evaluation
Pregnancy Amenorrhea, morning sickness, breast tenderness, bloating, history of sexual activity and improper contraception use Urine pregnancy test
Toxic ingestion History of ingestion, findings vary depending on substance and pattern of ingestion Varies depending on substance


Vomiting is a symptom that can be caused by a variety of conditions that affect different organ systems. When evaluating a child with vomiting it is important to identify conditions in which immediate medical intervention is needed.

The most common causes of vomiting are age dependent and can cross over age ranges (see the above table for differential diagnosis based on age). If a child has prolonged vomiting (>12 hours in a neonate, >24 hours in children younger than two years of age, or >48 hours in older children) they should have appropriate investigations.

If a patient displays any of the following red flags, it is important to watch them carefully and have a low threshold for intervention:

  • Lethargy and listlessness
  • Inconsolability and bulging fontanelle in an infant
  • Nuchal rigidity, photophobia, and fever in an older child
  • Peritoneal signs or abdominal distention (“surgical” abdomen)
  • Persistent vomiting with poor growth or development


(1) AccessMedicine | How to Cite Available at: Accessed 1/1/2011, 2011.

(2) Pediatric Care Online : Definition of Age Group Terminology Available at: Accessed 1/1/2011, 2011.

(3) Nausea and Vomiting In Infants and Children: Approach to the Care of Normal Infants and Children: Merck Manual Professional Available at: Accessed 1/15/2011, 2011.

(4) Allen K. The vomiting child–what to do and when to consult Aust.Fam.Physician 2007 Sep;36(9):684-687.

(5) Scorza K, Williams A, Phillips JD, Shaw J. Evaluation of nausea and vomiting Am.Fam.Physician 2007 Jul 1;76(1):76-84.


Writer: Bing Wei Wang

Edited: Dianna Louie

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